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Re: PowerPC gas/ immediate range checking?

> Date: Fri, 25 May 2001 14:58:51 -0500
> From: Becky Gill <>

> I have a question about gas on PowerPC.  The assembly instruction
> addi	r3,r3,0xdead
> Generates this warning:
> Error: operand out of range (000000000000beef not between -32768 and 32767)
> However, this immediate value is perfectly valid for the addi instruction.  It
> looks as though gas is treating it as unsigned by default, filling in with
> zeroes, and then range checking that number. This results in an incorrect
> error, since the above instruction is valid.
> So, 2 questions:
> 1) Why is gas implemented as it is currently?  Is this intentional?
> 2) Is there a way to get around this problem when hand-coding assembly?

0xdead is the 32-bit value 0x0000dead.  You can't add this to a
register in a single instruction.  Instead, you must do:

addis r3,r3,-1
addi r3,r3,0x10000-0xdead

If you really meant to add -0x2153, it's probably better to write that.

GAS performs this check mostly to catch machine-generated operands that
overflow, for instance

Lbar:	addi r3,r3,Lfoo-Lbar



where it isn't obvious that the operand would overflow.

- Geoffrey Keating <>

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